Abrasive article



UNITED STATES PA'IENT OFFICE z.mm

simor to 1110 Cnrborundum Compuy.

Nimra Falls, N. Y. a cnrporation of Dela.ware

Applicatlon September 6, 1941, Serie! No. 409,812 11 Claims. ((21. 51-298) 'I'his invention relates te bonded abrasive articles, and more particularly te abrasive articles in which the abrasive portions of the articles are suppqrted by metallic or other rigid means, such as metal backing plates or side plates secured to the flat feces of abraslve sections, metal or other rigicl rings tastened to the back or inner suriece of annular-shaped abrasive articles, or spndles attached to various abrasive shapes for the purpose of mounting on grinding apparatus. Especially the invention concerns the means of securing these supporting plates, rings, spindles and the like to the abrasive purtions of the articles.

This appiication is a continuation-in-part of application Serial No. 303,279 filed November 7, 1989.

The inventon has been i'ound D8tticularly applicable to the making of disc-shabed grinding wheels edapted to be mounted for grlnding with the fiat side face of the wheel. Therefore, tor the purposes of simplicity and clarity, the invention w111 be descrbed mostly as itapplies to the making of such disc wheels.

It has been found in the past that many heavy duty grindng operations een be periormed most efiiciently by presenting the work to the flat mee of a disc-shaped grnding wheel. However, this type of grinding operation subjects the wheel to extremely high stresses and strains, particularly that part of the wheel where the abrasive section is jined te the backing plate or mounting. As a result, iailure 01' the wheel frequentiy oceurs sufliciently heat resistent to stand up under the heat of heavy duty grinding operations ior the home] lite of the abrasive portion at the wheel,

which can be operated at high grinding speeds,

which will be resistent to irerosene, oils, caustic,

hydrocarbons and other cooling agents used in because of weakness 0! the wheel at the jint caused in wet grinding by attack on the rubber layer by cooling agents such as kerosene, oils and other hydrocarbon cooling agents.

An object of the present inventon is te provide an improved means of securing bonded abrasive sections to rigid, metal supporting or mounting plates, rings, spindles and the iike.

Another object of the present invention is to provide en improved bonded abrasive article in which the bonded abrasive body of the article is strongly and iirmly secured to a backing plate, ring, spindle or the like.

Another object of the invention is to provide a. backed srinding wheel or disc which wiil be wet .grinding and dan thereiore be used tor both wet end dry grinding, a.nd which will possess a high energy absorption power and a high rate of demping of vibrations set up in grinding.

In accordance with the present invention, an a.brasive article is provided with a metallic supporting or mounting means secured to the bonded abrasive section by means of en intermediate bondng layer (herein referred to as a tie bond) which is strongly adherent to both the metai supporting means and to the bonded abrasive section, a.nd which retains the greater part of ts strength in the presenee 0! cooling agents and extreme temperatures involved in grinding operations. A specific application is the attachment of rigid, metal backing plates to the backs 013 discshaped grinding wheels tor use in heavy duty side grinding operations. A tie bond material which has been discovered to be highly etiective is pulychloroprene which has been suitably compounded. Another highly satisiactory tie bond materie! is the copolymer o! butadiene (divinyi) wlthacrylanitrile. Among ether vulcanizable synthetic elastic materials which are satisfactory are poiyvinylchloride, butadiene (divinyl) polymers, pclyethylene sulphide, polybromoprene, copolymers of butadiene (dvinyl) wth styrene, copoiymers of butadene (divnyl) wth methyl methacrylate, copolymers of butadiene (divinyl) wth isobutylene, copoiymers of butadiene (dvinyi) wth c oumarone or indene, copolymers of butdiene (divinyl) wth vinylidene chloride, copolymers of butadene wth chloromethacryiic ester, copolymers 01 chloroprene wth acrylonitrile, copolymers of chlorcprene wth styrene, copolymers of chloroprene wth methyl methacrylate, and other copolymers 01! butadiene or halogen-substtuted butadienes wth polymerizable compounds to Iorm vulcanizable elastics; also such straight and mixed piastics een be modified by the use of plasticizers and other modii'ylng agents.

In the drawing, which iilustrates one embodiment of the invention:

Figure 1 represents a front plan view of a discshaped grinding wheel embodying the present invention.

Figure 2 is a sectional view taken along the line 11-11 of Figure 1.

shown.)

The disc-shaped grinding wheel illustratd in Figures 1 and 2 consists of a. bonded abrasive .section 5 of any dcsired thlckness and diameter,

havi ng a flat grinding race 6 and an opposite supporting face The abrasive section 5 is composed of abrasive grain such as crystalline aluminum oxide or.silicon carbide suitably bondcd. The bond may be a vitri fled ceramic material, or it may be a silicate, or a resin or a rubber compound. As a support to provide added strength during grinding and to provide a means for mounting, the abrasive section 5 is provided with a steel backing plate & rigldly and adhesively attached to the supporting iace I of the abrasive section 5 by means of an intermediate layer of tie bond 9. 'I'o assist in the adherence of the tie bond 9 to the abrasive section 5 and metal plate 8, the supporting face 0! the abrasive section and the inner 1'ace I0 of the steel plate are properly treated prior to assembly. The backing plate 8 is provided with a center arbor hole H and three bolt holes |2 for Iastening the backed wheel to a mounting plate on the grinding machine. (The mounting plate is not As the above description and drawing show, the

final grinding Wheel is composed of three main parts, nameli, the abrasive section, the backing plate, and the tie bond uniting the abrasive section and the backing plate. In making such a wheel according .to the present invention, the

followng steps are carried out.

(A) Preparation of the abrasive section for plate for bondbonding.

will be discussed now under the separate headings above named.

(A) Bonded abrasive sections can-he united to metal supports by means of the tie bonds of the present invention irrespective of the type of bond used in the abrasiv'e section; highly satisfactory results have been obtained with resin, vitrifiecl, silicate and rubber-bonded abrasive sections. The abrasive sections are molded and. formed by any one of the well known methods of making bonded abrasive shapes. 'Iheabrasive section 0! the specific wheel illustrated consists 01 a single disc of bonded abrasive materialwhich can be any desired diameter and thlckness. However, ths continuous disc of abrasive may be replaced by a plurality of segments with the adjoining abrasive segments ither suitably cemented at their adjacent races o r separated by clearance spaces so as to present in use a discontinuous grinding surface.

In preparing the bonded abrasive section for combination with the metal backing, the supporting face of the p.brasive is cleaned with a. wire brush and any loose dust or dirt removed by an air blast. On the clean, dry supporting face of the wheel, one or more thin coatings of cement are applied, and the wheel dried after each application of cement. After the last coating ofcement has been applied and dried, the wheel is heated in an oven to a temperature of 2150 F. A cement for applying to the supporting face of the wheel when polychloroilrene tie bond material is employed can be made from vulcanizable compounded polychloroprene broken down to cement form in a solvent such as benzol or toluol. Two cements which have been found to be hlshly satisfactory for this purpose are ones sold on the market as Bostik M-117 and Bostik M-162.

(B) In the wheel illustrated, the backing plate is of mild steel out the same diameter as the abrasive section. The backing plate does not necessarily have to be of a size to cover the entire back of the abrasive section and may be of a. different material and thlckness; It may also have other means of machine mounting than the centrally-located bolt holes of the depicted ernbodiment.

The steel backing plate is flrst properly cleaned to remove all oil and dirt. The plate suriace for contact with the tie bond is then prepared toreceive the cement. and tie bond. This can be done by the use of an ordinary commercial pickling procedure followed by washing and drying. which. when used in connection with the present ti bonds, gives an entirely satisfactory surface for adhesion. After the plate has been prepared as above, lt is given one or more coatings of a cement similar to that used on the supporting face of the abrasive section. After the cement has been dried, the plate is ready for use.

((2) The intermediate layer referred to herein as the tie bond consists of a layer of soft, pliable, resilient material in the form of a thin sheet approximately 3,"-;;" in thickness, although the thlckness may vary somewhat from these figures. By selection of the proper thickness of this intermediate layer, the desired degree of resilience, i..e. resistance to mechanical shock, of the wheel can be closely controlled. Before use, the sheet o1 tie bond material is wiped clean and dry on both sides and a. coating of cement such as that used on the backing plate and the abrasiv sec tion is applied to each side and allowed to dry.

As a tie bond material, polychloroprene, especially when properly compounded, has been found to be highly efiectiVe in bonding the backing plate to the abrasive section. By the addition of a filler such as soft carbon black in suftlcient quantities, a hond of extremely high strength has been obtained. Other flllers may be used to replace part or all of the soft carbon black. as, for example, channel black or mineral flllers such as blanc fixe, natural whiting, Dixie clay and the like, although soft carbon black is the preferrecl filler and produces the best results. Also, a part of the polychloroprene can be replaced by a natural rubber or a reclaimed rubber.

A tie bond material which is highly satisfac= tory for the present use is made of the following ingredients compounded and sheeted to the desired thlckness on a roll mill.

Parts by weight Polychloroprene Extra light calcined magnesia 4 Zinc oxide 5 Soft carbon black 200 Cottonseed 011 5 Sulfur---- 1 Phenyl-beta-naphthylamine 2 Polychloroprene, wh'en it is properly compounded, as a fundamentai or basic substance for tie bonds has been found to give very satisfac tory results. It is a polymer of chloroprene, otherwise known as 2 chloro-1, 3-butadiene having the iprmula CH2;ChCCI2CH2, and may be classified as being a halogen-substituted butadiene. A similar substance particularly eflectiVe as a tie bond is the copolymer of butadiene (divinyl) with acrylonitrile. Other compounds whlch een be used lnstead of polychloroprene or butadiene-acryionitrile wpolymers are polymers of butadine (divinyl) polyethylene sulphide and copolymers thereoi'. polymers and copolymers of vinyl chloride and vinyl acetate copolymers of chloroprene and ai'lonltrile, copolymers of butadiene (divinyl) with styrene, copolymers of butadiene (divinyl) with vinylidene chloride, co-

polymers of butadiene (divlnyl) with methyl methacrylate, copolyniers of -butadlene (divinyl) with coumarone or ihdene, and copolymers of chloropr'ene with styrene, or methyl methacry. late. These are all substances having physical propertles somewhat simllar to holychloroprene. They are materials of high molecular vveight and form tough, resilient. pliable sollds which are vuloanizable. In vulcinized form, they withstand the heat evolved in diir z rinding and are resistant te water and many h:rdrocarbon cooling agents used in wet grinding.

(D) Atter the tie bond has been prepared in grinding are damped out quiekly. As a result.

bui. a simple pickling treatment of the metal suf not require immediat asserfioling, but can be.

sheet form and haal been cut to the desired size tor use with the backing plate and abrasive sectlon, the three parts are assembled. The sheet of tie hond is placed upon the metal plate and smoothed down by runnlng a roller over its suriace to insure complete contact with the metal plate and to remove any air bubbles which may be trapped between the sheet and the metai: The abrasive sectlon which has been kept in an oven at 250 F. is then removed and, while stlll ilces. 'I'his saves alsq the need of hammering the piates after the warplng prqduce d by sandblastlng. Again,- the parts afterpreparation do st0red for later assembly at the convenience of the operator and availability of presses. Also, in curlng the present articles, the temperature and pressute of ciire can be vari ed considerably withq1t the danser of overcuring and its resultant ioss of strength. These and other features lead to economies of manufacture not heretofore athot, is placed on the tie bond sheet and. metai plate. The assembly is centered on a mandrei to hold the parts in place during cure and the whole placed in a hot press. The tie hond is cured in the hot press undera pressure of 100-600 pounds per square inch at a temperature of 290- 300 LF'. Thirty mlnutes is usually suillcient to adequately cure the wheel. For best results, the tie bond should be ct1red always under a prensure and temperatiire suiiicient to cause it to extrude slightly at the edg'es trom between the backing plate and the abrasive.

Abrasive wheels and, discs of the present invention possess several beneflcial properties which not only improve the gener al grinding characterlstics of the wheels, but also exteud their fleld of usefulness. For example, the present abrasive wheels have a long temperature range of serviceability extending trom to 300 Fahrenheit. Their retention of mechanica] strength at high temperatures results in an increased factor of safety at normal operating speeds and also permits of higher speeds of operation when deslrable. Also by reason of the high heat conductivity of the tie bond material, much of the heat generated in the abrasive section liuring use is quickly conducted through the tie bond 1ayer to the metal support, where it is more easily dissipted by radiation, thus removing much of the danger of lcalized build-up of heat in the abrasive portions and thereby increasing the strength of the Whel.

Anothet important property of wheels of the present inntlon. is their increased ability to absorb energ, a feature particularly important in grinding v heels which in the process of grinding are sublected to a repeated series of vibrations or shocks from contact with the work being giomd. This ability to absorb energy is directly related to the ability to take up mechanical shock without damae to the wheel. This increased ability of the iresent wheels to absorb energy is coupled with a high rato of demping. so that, as a result, any vibrations fromthe shocks of sired to claim:-

talnable.

It is not intended that the invention should be limited to the particular embodiment of wheel illustrated, as like objects and advantages are obtained in various other abrasive articles where it is necessary to secure bonded abrasive sectlons to metal or other rigid supporting or mounting means. For instahce, similar disc wheels can be made in whlch the abrasive setion is made of a plurality of individual segments properly spaced. one from the other, to present a discontinnous grinding surface. Likewlse, wheels for peilpheral grlnding may have supp rting plates sirnilar- 1y secured to their flat side feces for added strength.

The present invention can also 'be used in the making'of abrasve grinding rings or other sh.ped segments when it is desired to secure a metal support or mounting to the back or sides of the segment, or when, in the case of annulargrinding shapes, it is desired to secure a metal rin to the internal or external circumferential surface of the ring away frorn the grinding surface as a reinforcement or means of mounting. Also as en example of the application of the present lnventlon, a number of large abrasive segments "een be attached to a center ring of steel or other rigid materie! by means of a tle bond of vulca'nizable synthetic elastic such as polychloroprehe to form a. pulp-wheel.

Likewise, small dental grinding stones such as cones and other shapes can be attachedto steel mounting spindles by means of a vulcanizable tle bond such as set forth herein.

Having described the inventioh fully, it is de- 1. A bonded abrasive ar-ticle comprisixig a bonded abrasive body, a rigid metal supporting means and an intermediate cementing layer between said bolided abraslve b'ody and saidrigd metal supportlng mearis adhesively unltlng the two, said cementing laver comprising polychloro-- prene compounded with a substttntial amount of a flller such as carbon black, and having an ad hesive strength with respect to the bonded abrasive body and the rigid metal supporting means substantially in excess of that of the rubber bands similarly ernployed.

2. A bonded abraslve article comprising a bonded abrasive body, a rigid metal supporting means, and an intermediate cementlng layer he tweeu said bonded abraslve body and said rigid metal supportng means adhesively unlting the two, said cementing layer comprlsing a polymerized halogen-substituted butadlene compounded with a substantial amount of a flller such as carbon black, and havng an adhesive strength with respect tothe bonded abraslve body and the rigld metal supporting means substantlally in excess of that of the rubber bonds slmilarly employed.

3. A bonded abrasive article comprisnzg a bonded abrasive body. a rigid metal supporting means, a.nd en intermedate cementing lay'er between said bonded abrasve body and said rlgd metal supporting means adhesively uniting the two, seid cementing layer comprising a.

member of the group consisting of polychloroprene, polychloroethylene, polydivinyl and polybetween said bonded abrasve body and sad rigid metaL supporting means adhesively uniting the two, said cementing layer comprising a. copolymer of polychlroprene and a copolymerza.ble resln compounded with a. substantial amount of a flller such as carbon black, end having an adhesive str ength Wth respect to the bonded abrasive body and the rigid metal supporting means substantially in excess of that of the rubber bonds simlarly employed.

5. A bonded abrasive article comprsing a bonded abrasive body, a rigid metal supporting means, and an ntermedate cementing layer between said bonded abrasive body and saidrigid metal supporting means adhesively uniting the two, sad cementing layer comprising a copolymer of butadiene and a copolymerizable resin compounded with a substantie] amount of a flller such as carbon blck, and having en adhesive strength with respect to the bonded abrasive body and the rigid metal supportng means substantially in excessof that of the rubber bonds similarly employed.

6. A bonded abrasive article comprising a bonded abrasive body, a rigid metal supporting means, and an intermediate cementing layer between said bonded abrasive body and said rigd metal supporting means adhesively unitng the two, said cementing layer comprising a copo1ymer of butadiene and acrylonitrile compounded with a. substantial amount of a. filler such as carbon black, and having an adhesve strength with respect to the bonded abrasive body and the rigid metal supportlng means substantially in excess of that of the rubber bonds similarly employed.

7. A bonded abrasive article comprising a. bonded abrasive body, a rigid metal supporting means, and an ntermediate cementing layer between said bo1'1'ded abrasive body and said rigd metal supporting means adhesively uniting the two, sald cementing 1ayer comprsing a member of the group consisting of polychloroprene, polychloroetlurlene, polydivinyl, and polyethylenesulphide modifled by the copolymerization therewith of a copolymerizable resin compounded wth a substantial amount of a fi1ler such as carbon black, and havng en adheslve strength wth respect to the bonded abraslve body and the rigld meta1 supp0rting means substantally in excess of that of the rubber bonds smlarly employed.

8. A bonded abresve erticle comprsng e. bonded abrasive body, e. rlgid metal supporting means, end en ntermedate cementing layer between said bonded abrasive body end sa.d rigd metal supporting means adhesively uniting the two, sad cementing layer comprising a copolymer of butadiene and styrene compounded wlth a substantial emount of a fl11er such as carbon black, and havng en edhesive strength with respect to the bonded abrasive body and the rlgid metal supporting means substantally in excess of that of the rubber bonds smilarly employed.

9. A bonded abrasive artc1e comprising a bonded abrasive body, a rigld metal supportng means, and an intermediate cementng 1eyer between said bonded abrasive body and said rlgid metal supporting means adhesively uniting the mer of polychloroprene anda, copolymerzable resin selected from the group consisting of acrylonitrile, styrene, methyl methacrylate, isobutylene, coumarone, ndene, vnylidene chloride and chloromethacrylic ester compounded with a substantial amount of a flller such as carbon black and having an adhesve strength with respect to the bonded abrasive body and the rig1d metal supportng means substantially in excess of that of the rubber bonds similarly employed.

10. A bonded abrasive artic1e comprising a bonded abrasive body, a rlgid metal supporting means, and an intermediate cementing 1ayer between said bonded abrasive body and said rigid metal supportng means adhesvely unit- :lng the two, said cementing layer comprising a copolymer of butadiene and a copolymerzable resn selected from the group consisting of acrylontrile, styrene, methyl methacrylate, isobutylene, coumarone, indene, vinyldene chloride, polyethylenesulphide, and chloromethacrylic ester, compounded with a substantial amount of a filler such as carbon black, and having an adhesive strength with respect to the bonded abrasive body and the rigd metal supporting means substantially in excess of that of the rubber bonds smilarly employed.

11. A bonded abrasive artic1e comprising a bonded abrasive body, a rigd metal supportng means, and en intermediate cementing layer between said bonded abrasve body and said rigid metal supporting means adhesively uniting the two, said cementng 1ayer comprsing a member of the group consisting of polychloroprene, polychloroethylene, polydivinyl, and polyethylenesulphide modifled by the copolymerization therewith of a. copolymerizable resin se1e cted from the group consstng of acrylonitrile, styrene, methyl methacrylate, sobutylene, coumarone, indene, vinylidene chloride and chloromethacrylic ester, compounded with a substantia.l amount of a filler such as carbon black, and havng en adhesive strength wth respect to the bonded abrasive body and the rigid metal supportng means substantially in excess of that of the rubber bonds 'similarly employed.

GARRET VAN NIMWEGEN. 

